High-frequency electrical connector

ABSTRACT

An electrical connector comprises an insulative shell having a floor; a first plurality of contacts extending through the floor, wherein the first plurality of contacts are disposed in a plurality of columns; a second plurality of contacts extending through the floor, wherein the second plurality of contacts are interspersed with the first plurality of contacts within the plurality of columns; and a conductive member adjacent the floor. The conductive member comprises a first plurality of openings, wherein the first plurality of contacts extend through the openings of the first plurality of openings; a second plurality of openings, wherein the second plurality of contacts extend through the openings of the second plurality of openings; and a first plurality of tabs, extending into openings in the insulative shell.

BACKGROUND

This disclosure relates generally to electrical interconnection systemsand more specifically to improved signal integrity in interconnectionsystems, particularly in high speed electrical connectors.

Electrical connectors are used in many electronic systems. It isgenerally easier and more cost effective to manufacture a system asseparate electronic assemblies, such as printed circuit boards (“PCBs”),which may be joined together with electrical connectors. A knownarrangement for joining several printed circuit boards is to have oneprinted circuit board serve as a backplane. Other printed circuitboards, called “daughter boards” or “daughter cards,” may be connectedthrough the backplane.

A known backplane has the form of a printed circuit board onto whichmany connectors may be mounted. Conductive traces in the backplane maybe electrically connected to signal conductors in the connectors so thatsignals may be routed between the connectors. Daughter cards may alsohave connectors mounted thereon. The connectors mounted on a daughtercard may be plugged into the connectors mounted on the backplane. Inthis way, signals may be routed among the daughter cards through thebackplane. The daughter cards may plug into the backplane at a rightangle. The connectors used for these applications may therefore includea right angle bend and are often called “right angle connectors.” Otherknown connectors include, but are not limited to, orthogonal midplaneconnectors and midplaneless direct attachment orthogonal connectors.

Connectors may also be used in other configurations for interconnectingprinted circuit boards and for interconnecting other types of devices,such as cables, to printed circuit boards. Sometimes, one or moresmaller printed circuit boards may be connected to another largerprinted circuit board. In such a configuration, the larger printedcircuit board may be called a “mother board” and the printed circuitboards connected to it may be called daughter boards. Also, boards ofthe same size or similar sizes may sometimes be aligned in parallel.Connectors used in these applications are often called “stackingconnectors” or “mezzanine connectors.”

Regardless of the exact application, electrical connector designs havebeen adapted to mirror trends in the electronics industry. Electronicsystems generally have gotten smaller, faster, and functionally morecomplex. Because of these changes, the number of circuits in a givenarea of an electronic system, along with the frequencies at which thecircuits operate, have increased significantly in recent years. Currentsystems pass more data between printed circuit boards and requireelectrical connectors that are electrically capable of handling moredata at higher speeds than connectors of even a few years ago.

In a high density, high speed connector, electrical conductors may be soclose to each other that there may be electrical interference betweenadjacent signal conductors. To reduce interference, and to otherwiseprovide desirable electrical properties, shield members are often placedbetween or around adjacent signal conductors. The shields may preventsignals carried on one conductor from creating “crosstalk” on anotherconductor. The shield may also impact the impedance of each conductor,which may further affect electrical properties.

Examples of shielding can be found in U.S. Pat. Nos. 4,632,476 and4,806,107, which show connector designs in which shields are usedbetween columns of signal contacts. These patents describe connectors inwhich the shields run parallel to the signal contacts through both thedaughter board connector and the backplane connector. Cantilevered beamsare used to make electrical contact between the shield and the backplaneconnectors. U.S. Pat. Nos. 5,433,617, 5,429,521, 5,429,520, and5,433,618 show a similar arrangement, although the electrical connectionbetween the backplane and shield is made with a spring type contact.Shields with torsional beam contacts are used in the connectorsdescribed in U.S. Pat. No. 6,299,438. Further shields are shown in U.S.Publication No. 2013/0109232.

Other connectors have the shield plate within only the daughter boardconnector. Examples of such connector designs can be found in U.S. Pat.Nos. 4,846,727, 4,975,084, 5,496,183, and 5,066,236. Another connectorwith shields only within the daughter board connector is shown in U.S.Pat. No. 5,484,310. U.S. Pat. No. 7,985,097 is a further example of ashielded connector.

Other techniques may be used to control the performance of a connector.For example, transmitting signals differentially may reduce crosstalk.Differential signals are carried on a pair of conductive paths, called a“differential pair.” The voltage difference between the conductive pathsrepresents the signal. In general, a differential pair is designed withpreferential coupling between the conductive paths of the pair. Forexample, the two conductive paths of a differential pair may be arrangedto run closer to each other than to adjacent signal paths in theconnector. No shielding is desired between the conductive paths of thepair, but shielding may be used between differential pairs. Electricalconnectors can be designed for differential signals as well as forsingle-ended signals. Examples of differential signal electricalconnectors are shown in U.S. Pat. Nos. 6,293,827, 6,503,103, 6,776,659,7,163,421, and 7,794,278.

In an interconnection system, such connectors are attached to printedcircuit boards, one of which may serve as a backplanes for routingsignals between the electrical connectors and for providing referenceplanes to which reference conductors in the connectors may be grounded.Typically the backplane is formed as a multi-layer assembly manufacturedfrom stacks of dielectric sheets, sometimes called “prepreg”. Some orall of the dielectric sheets may have a conductive film on one or bothsurfaces. Some of the conductive films may be patterned, usinglithographic or laser printing techniques, to form conductive tracesthat are used to make interconnections between circuit boards, circuitsand/or circuit elements. Others of the conductive films may be leftsubstantially intact and may act as ground planes or power planes thatsupply the reference potentials. The dielectric sheets may be formedinto an integral board structure such as by pressing the stackeddielectric sheets together under pressure.

To make electrical connections to the conductive traces or ground/powerplanes, holes may be drilled through the printed circuit board. Theseholes, or “vias”, are filled or plated with metal such that a via iselectrically connected to one or more of the conductive traces or planesthrough which it passes.

To attach connectors to the printed circuit board, contact pins orcontact “tails” from the connectors may be inserted into the vias, withor without using solder. The vias are sized to accept the contact tailsof the connector.

As in the case of the connectors that attach to the printed circuitboards, the electrical performance of printed circuit boards is at leastpartially dependent on the structures of the conductive traces, groundplanes and vias formed in the printed circuit boards. Further,electrical performance issues become more acute as the density of signalconductors and the operating frequencies of the connectors increase.Such electrical performance issues may include, but are not limited to,crosstalk between closely-spaced signal conductors.

SUMMARY

In accordance with embodiments, an electrical connector comprises aninsulative shell having a floor; a first plurality of contacts extendingthrough the floor, wherein the first plurality of contacts are disposedin a plurality of columns; a second plurality of contacts extendingthrough the floor, wherein the second plurality of contacts areinterspersed with the first plurality of contacts within the pluralityof columns; and a conductive member adjacent the floor. The conductivemember comprises a first plurality of openings, wherein the firstplurality of contacts extend through the openings of the first pluralityof openings; a second plurality of openings, wherein the secondplurality of contacts extend through the openings of the secondplurality of openings; and a first plurality of tabs, extending intoopenings in the insulative shell.

In some embodiments, the first plurality of tabs are slidable in theopenings in the insulative shell relative to the columns of contacts.

In some embodiments, each of the openings in the insulative shell has apair of opposed slots; and each of the first plurality of tabs isinserted into the pair of opposed slots.

In some embodiments, the first plurality of contacts are disposed in aplurality of pairs; within each column of the plurality of columns, eachpair of the plurality of pairs is disposed between two adjacent contactsof the second plurality of contacts.

In some embodiments, the conductive member reduces near end crosstalkbetween a first pair and a second pair diagonally adjacent to the firstpair by at least 2 dB over the frequency range from 5 to 28 GHz.

In some embodiments, each of the second plurality of contacts comprisesa mating contact portion and two contact tails, the mating contactportion comprises a contact surface, and each of the second plurality ofcontacts comprises a twisted region such that a line between the twocontact tails is transverse to the contact surface.

In some embodiments, the line between the two contact tails is at anangle to the contact surface between 35 and 55 degrees.

In some embodiments, a first of the two adjacent second contacts istwisted in a first direction relative to the contact surface; and asecond of the two adjacent second contacts is twisted in a seconddirection, opposite to the first direction, relative to the contactsurface.

In some embodiments, the floor comprises a plurality of surface portionsand a recessed portion, recessed relative to the surface portions; theplurality of surface portions extend through the first plurality ofopenings; and the conductive member is disposed within the recessedportion.

In some embodiments, the first plurality of contacts are disposed in aplurality of pairs; each of the plurality of pairs extends through asurface portion of the plurality of surface portions.

In some embodiments, the second plurality of contacts extend through therecessed portion.

In some embodiments, the first plurality of contacts and the secondplurality of contacts comprise mating contact portions and contacttails; the floor comprises a first surface and an opposed secondsurface; the mating contact portions of the first plurality of contactsand the second plurality of contacts extend from the first surface; thecontact tails of the first plurality of contacts and the secondplurality of contacts extend from the second surface; and the recessedportion comprises a recess in the first surface.

In some embodiments, the conductive member also comprises a secondplurality of tabs; and the second plurality of tabs press against thesecond plurality of contacts.

In some embodiments, the second plurality of contacts comprise firstsurfaces, facing a first direction, and opposing second surfaces; thesecond plurality of tabs press against the second plurality of contactsat the second surfaces.

In some embodiments, the second plurality of contacts comprise dimplesthat are concave in the second surfaces; the second plurality of tabscomprise tips; and the tips of the second plurality of tabs contact thesecond surfaces at the dimples.

In some embodiments, the tips of the second plurality of tabs arerounded such that the tips contact the dimples at at least two points.

In some embodiments, the second plurality of tabs are compliant beamsand exert a spring force against the second surfaces, biasing theconductive member in a second direction normal to the second surfaces;the floor comprises a plurality of surface portions and a recessedportion, recessed relative to the surface portions; the plurality ofsurface portions extend through the first plurality of openings suchthat edges of the conductive member abut the surface portions so as tocounter spring forces biasing the conductive member in the seconddirection.

In some embodiments, the first surfaces of the second plurality ofcontacts comprise a selective plating of gold.

In some embodiments, the second plurality of contacts comprises at least16 contacts; and the conductive member electrically connects the atleast 16 contacts.

In some embodiments, the first plurality of contacts comprisedifferential signal contacts; and the second plurality of contactscomprise ground contacts.

In some embodiments, the conductive member comprises a metal member.

In some embodiments, the metal member comprises a metal sheet with theopenings of the first plurality of openings and the second plurality ofopenings and the tabs formed therein.

In accordance with further embodiments, a printed circuit boardcomprises a plurality of signal traces; a plurality of ground layers;and the electrical connector as mentioned above mounted to the printedcircuit board, wherein the first plurality of contacts are connected tothe signal traces; and the second plurality of contacts are connected tothe ground layers.

In accordance with further embodiments, a conductive member comprises aconductive sheet with a first plurality of openings and a secondplurality of openings, wherein the first plurality of openings aredisposed in a plurality of columns, and the second plurality of openingsare interspersed with the first plurality of openings within theplurality of columns; and a first plurality of tabs, disposed at edge ofthe conductive sheet and bendable at an angle relative to the conductivesheet.

In some embodiments, the conductive member also comprises a secondplurality of tabs; and each of the second plurality of tabs is disposedin each of the second plurality of openings.

In some embodiments, each of the second plurality of tabs is a compliantbeam.

In some embodiments, the second plurality of tabs comprise tips; and thetips of the second plurality of tabs are rounded.

In some embodiments, each column of the plurality of columns is offsetin the column direction with respect to adjacent columns.

In accordance with further embodiments, a method of forming anelectrical connector, the method comprises placing a conductive memberadjacent to a floor of a shell of the electrical connector; inserting afirst plurality of contacts through a first plurality of openings in theconductive member such that the first plurality of contacts arepositioned in columns on the floor; and inserting a second plurality ofcontacts through a second plurality of openings in the conductive membersuch that the second plurality of contacts are positioned in thecolumns, wherein a first plurality of tabs of the conductive memberextend into openings in the shell such that the conductive member areattached to the shell.

In some embodiments, a second plurality of tabs on the conductive memberpress against the second plurality of contacts such that the secondplurality of contacts are electrically connected through the conductivemember.

In some embodiments, forming the conductive member by stamping in ametal sheet the openings of the first plurality of openings and thesecond plurality of openings and the first plurality of tabs and thesecond plurality of tabs.

In some embodiments, the method further comprises plating a firstsurface of the second plurality of contacts with a noble metal; andinserting the second plurality of contacts comprises sliding each of thesecond plurality of tabs over a second surface of the second pluralityof contacts.

In some embodiments, placing the conductive member adjacent to the floorof the shell comprises receiving portions of the shell within the firstplurality of openings, wherein the portions of the shell electricallyinsulate the first plurality of contacts from the conductive member.

BRIEF DESCRIPTION OF DRAWINGS

For a better understanding of the disclosed technology, reference ismade to the accompanying drawings, which are incorporated herein byreference and in which:

FIG. 1 is an exploded view of a high speed, high density electricalconnector, a backplane and a daughter board;

FIG. 2 is a perspective view of a backplane connector in accordance witha first embodiment of a high speed, high density electrical connector;

FIG. 2A is an enlarged view of region A in FIG. 2;

FIG. 3 is an exploded view of the backplane connector of FIG. 2;

FIG. 3A is an enlarged view of region B in FIG. 3;

FIG. 4 an another exploded view of the backplane connector of FIG. 2,wherein a conductive member is attached to an insulative shell;

FIG. 4A is an enlarged view of region C in FIG. 4;

FIG. 5 is a top view of an insulative shell with a conductive memberattached in accordance with second embodiment of a high speed, highdensity electrical connector;

FIG. 5A is an enlarged view of region D in FIG. 5;

FIG. 5B is a sectional view taken along line E-E in FIG. 5;

FIG. 6 is a perspective view of second contacts in accordance with athird embodiment of a high speed, high density electrical connector; and

FIG. 7 is a partial top view of a connector footprint on a printedcircuit board.

DETAILED DESCRIPTION

The inventors have recognized and appreciated that the operating speedof an electrical connector may be improved with a conductive memberadapted to be mounted adjacent a floor in a connector housing. In oneimplementation, such a conductive member may be made by forming one ormore cutouts in a sheet of conductive material. The cutouts may bearranged such that, when the conductive member is disposed across amating interface of the connector, the conductive member is inelectrical contact with at least some of the ground conductors in theconnector, but not with any conductive elements adapted to be signalconductors. For example, the cutouts may be aligned with the signalconductors at the mating interface so that each signal conductor extendsthrough a corresponding cutout without making electrical contact withthe conductive member. Though, alternatively or additionally, such aconductive member may be integrated into the connector near the contacttails.

Such techniques may be used alone or in any suitable combination,examples of which are provided in the exemplary embodiments describedbelow.

Referring to FIG. 1, an electrical interconnection system 100 with twoconnectors is shown. The electrical interconnection system 100 includesa daughter card connector 120 and a backplane connector 150.

Daughter card connector 120 is designed to mate with backplane connector150, creating electronically conducting paths between a backplane 160and a daughter card 140. Though not expressly shown, interconnectionsystem 100 may interconnect multiple daughter cards having similardaughter card connectors that mate to similar backplane connections onbackplane 160. Accordingly, the number and type of subassembliesconnected through an interconnection system is not a limitation.

FIG. 1 shows an interconnection system using a right-angle, separablemating interface connector. It should be appreciated that in otherembodiments, the electrical interconnection system 100 may include othertypes and combinations of connectors, as the invention may be broadlyapplied in many types of electrical connectors, such as right-angle,separable mating interface connectors, mezzanine connectors and chipsockets.

Backplane connector 150 and daughter card connector 120 each containsconductive elements. The conductive elements of daughter card connector120 are coupled to traces, of which trace 142 is numbered, ground planesor other conductive elements within daughter card 140. The traces carryelectrical signals and the ground planes provide reference levels forcomponents on daughter card 140. Ground planes may have voltages thatare at earth ground or positive or negative with respect to earthground, as any voltage level may act as a reference level.

Daughter card connector 120 includes a plurality of wafers 122 ₁ . . .122 ₆ coupled together, with each of the plurality of wafers 122 ₁ . . .122 ₆ having a housing and a column of conductive elements. In theillustrated embodiment, each column has a plurality of signal conductorsand a plurality of ground conductors. The ground conductors may beemployed within each wafer 122 ₁ . . . 122 ₆ to minimize crosstalkbetween signal conductors or to otherwise control the electricalproperties of the connector.

In the illustrated embodiment, daughter card connector 120 is a rightangle connector and has conductive elements that traverse a right angle.As a result, opposing ends of the conductive elements extend fromperpendicular edges of the wafers 122 ₁ . . . 122 ₆.

Each conductive element of wafers 122 ₁ . . . 122 ₆ has at least onecontact tail, shown collectively as contact tails 126 that can beconnected to daughter card 140. Each conductive element in daughter cardconnector 120 also has a mating contact portion, shown collectively asmating contact portions 124, which can be connected to a correspondingcontact in backplane connector 150. Each conductive element also has anintermediate portion between the mating contact portion and the contacttail, which may be enclosed by or embedded within a wafer housing.

The contact tails 126 electrically connect the contacts within daughtercard and connector 120 to conductive elements, such as traces 142 indaughter card 140. In the embodiment illustrated, contact tails 126 arepress fit “eye of the needle” contacts that make an electricalconnection through via holes in daughter card 140. However, any suitableattachment mechanism may be used instead of or in addition to via holesand press fit contact tails.

In the illustrated embodiment, each of the mating contact portions 124has a dual beam structure configured to mate to a corresponding matingcontact portion 154 of backplane connector 150. The conductive elementsacting as signal conductors may be grouped in pairs, separated by groundconductors in a configuration suitable for use as a differentialelectrical connector. However, other embodiments are possible forsingle-ended use in which the conductive elements are evenly spaced withor without designated ground conductors separating signal conductors orwith a ground conductor between signal conductors.

In the embodiments illustrated, some conductive elements are designatedas forming a differential pair of conductors and some conductiveelements are designated as ground conductors. These designations referto the intended use of the conductive elements in an interconnectionsystem as they would be understood by one skilled in the art. Forexample, though other uses of the conductive elements may be possible,differential pairs may be identified based on preferential couplingbetween the conductive elements that make up the pair. Electricalcharacteristics of the pair, such as its impedance, that make itsuitable for carrying a differential signal may provide an alternativeor additional method of identifying a differential pair. As anotherexample, in a connector with differential pairs, ground conductors maybe identified by their positioning relative to the differential pairs.In other instances, ground conductors may be identified by their shapeor electrical characteristics. For example, ground conductors may berelatively wide to provide low inductance, which is desirable forproviding a stable reference potential, but provides an impedance thatis undesirable for carrying a high speed signal.

For exemplary purposes only, daughter card connector 120 is illustratedwith six wafers 122 ₁ . . . 122 ₆, with each wafer having a plurality ofpairs of signal conductors and adjacent ground conductors. As pictured,each of the wafers 122 ₁ . . . 122 ₆ includes one column of conductiveelements. However, the disclosed technology is not limited in thisregard, as the number of wafers and the number of signal conductors andground conductors in each wafer may be varied as desired.

As shown, each wafer 122 ₁ . . . 122 ₆ is inserted into front housing130 such that mating contact portions 124 are inserted into and heldwithin openings in front housing 130. The openings in front housing 130are positioned so as to allow mating contact portions 154 of thebackplane connector 150 to enter the openings in front housing 130 andallow electrical connection with mating contact portions 124 whendaughter card connector 120 is mated to backplane connector 150.

Daughter card connector 120 may include a support member instead of orin addition to front housing 130 to hold wafers 122 ₁ . . . 122 ₆. Inthe pictured embodiment, stiffener 128 supports the plurality of wafers122 ₁ . . . 122 ₆. Stiffener 128 is, in the embodiment illustrated, astamped metal member. However, stiffener 128 may be formed from anysuitable material. Stiffener 128 may be stamped with slots, holes,grooves or other features that can engage a wafer.

Similarly, contacts in backplane connector 150 are coupled to traces, ofwhich trace 162 is numbered, ground planes or other conductive elementswithin backplane 160. When daughter card connector 120 and backplaneconnector 150 mate, contacts in the backplane connector and conductiveelements in the daughter card connector mate to complete electricallyconductive paths between the conductive elements within backplane 160and daughter card 140.

Backplane connector 150 includes a backplane shell 158 and a pluralityof contacts. The contacts of backplane connector 150 are held within theshell 158, which may be formed of an insulative material. In someembodiments, the contacts extend through floor 514 of the backplaneshell 158 with portions both above and below floor 514. Here, theportions of the contacts that extend above floor 514 form mating contactportions, shown collectively as mating contact portions 154, which areadapted to mate to corresponding conductive elements of daughter cardconnector 120. In the illustrated embodiment, mating contact portions154 are in the form of blades, although other suitable contactconfigurations may be employed, as the disclosed technology is notlimited in this regard.

Tail portions, shown collectively as contact tails 156, of the contactsextend below the shell floor 514 and are adapted to be attached tobackplane 160. Here, the tail portions are in the form of a press fit,“eye of the needle” compliant sections that fit within via holes, showncollectively as via holes 164, on backplane 160. However, otherconfigurations are also suitable, such as surface mount elements, springcontacts, solderable pins, etc., as the disclosed technology is notlimited in this regard.

FIG. 2 shows a perspective view of a backplane connector 200 suitablefor use with a daughter card connector (e.g., the daughter cardconnector 120 shown in FIG. 1), in accordance with some embodiments. Inthis example, the contacts in backplane connector 200 generally includea first plurality of contacts 210 and a second plurality of contacts220, which are accommodated in an insulative shell 230. In someembodiments, the first contacts may be adapted to be signal conductors,while the second contacts may be adapted to be ground conductors. Thefirst contacts 210 are disposed in a plurality of columns. For example,first contacts 2101, 2102 and 2103 are disposed in a column. The secondcontacts 220 are interspersed with the first contacts 210 within eachcolumn. In the illustrated embodiment, the first contacts 210 aredisposed in a plurality of pairs, for example, for transmitting signalsdifferentially. The adjacent pairs of the first contacts 210 within acolumn are separated by at least a second contact 220. For instance,within each column, each pair of the first contacts is disposed betweenand adjacent two second contacts. The pair of the first contacts 2101,the pair of the first contacts 2102 and the pair of the first contacts2103 are disposed between and adjacent two second contacts 220respectively. The ground conductors may be employed to reduce crosstalkbetween signal conductors or to otherwise control one or more electricalproperties of the connector. The ground conductors may perform thesefunctions based on their shape and/or position within the column ofcontacts within a wafer or position within an array of contacts formedwhen multiple wafers are arranged side-by-side.

While a connector with differential pairs is shown in figures forpurposes of illustration, it should be appreciated that embodiments arepossible for single-ended use in which contacts are evenly spacedwithout designated ground conductors separating designated differentialpairs, or with designated ground conductors between adjacent designatedsignal conductors for some or all of the columns.

The backplane connector 200 further includes a conductive member 300,which is visible in the exploded view of FIG. 3. The conductive member300 is disposed adjacent the floor 232 of the insulative shell 230, asshown in FIG. 4. The conductive member 300 comprises a first pluralityof openings 310 and a second plurality of openings 320. For instance,the conductive member 300 may be a conductive sheet 302 with the firstopenings 310 and the second openings 320. In an assembled connector, thefirst contacts 210 extend through the first openings 310, and the secondcontacts 220 extend through the second openings 320. The mating contactportions of the first and second contacts 210 and 220 extend above theconductive member 300. The first openings 310 are arranged in aplurality of columns. The second openings 320 are interspersed with thefirst openings 310 within each column. For instance, the first andsecond openings 310 and 320 may be adapted to receive the mating contactportions of the first and second contacts 210 and 220 shown in FIG. 2,respectively. On the other hand, each of the first openings 310 may beadapted to receive two mating contact portions of two first contactsshown in FIG. 2, but without making electrical connection with either ofthe mating contact portions. In the illustrated embodiment, two firstcontacts 210 pass through each of first openings 310. Between any twoadjacent first openings 310, there is a second opening 320. One secondcontact 220 passes through each of second openings 320. The secondopenings 320 may be adapted to make electrical connection betweenconductive member 300 and the mating contact portions of the secondcontacts. The connections, in some embodiments, may be made by sizingopenings adapted to receive second contacts to be approximately the samesize as the second contacts in one or more dimensions. However, itshould be appreciated that aspects of the present disclosure are notlimited to this.

Moreover, the second openings 320 may be shaped and positioned so thatthe conductive member 300 is in electrical contact with mating contactportions of second contacts 220, but not with mating contact portions offirst contacts 210. In this manner, the second contacts 220 may beelectrically connected to each other via the conductive member 300.

In some embodiments, each column of the first and second contacts 210and 220 is offset in the column direction with respect to adjacentcolumns of the first and second contacts 210 and 220. Thus, the pairs offirst contacts in a column are diagonally adjacent to the correspondingpairs of first contacts in adjacent columns. In the cases that the firstcontacts serve as signal conductors, even with diagonal pairs of signalconductors, the conductive member 300 can reduce crosstalk between them.Near End Crosstalk (NEXT), for example, may be reduced in this way. Theconductive member 300 has an important benefit in reducing cross-talk athigher frequencies. The conductive member 300 can reduce crosstalkbetween diagonal pairs of signal conductors by at least 2 dB over thefrequency range from 5 to 28 GHz.

In some embodiments, such a conductive member 300 may be formed bystamping a preform with appropriate patterns of openings and tabs (ifany). Though, other materials may be used instead of or in addition tosuch a preform. A sheet of metal material, for example, may be used.

In some embodiments, the conductive member 300 further includes a firstplurality of tabs 330, extending into openings 238 in the insulativeshell 230, as shown in FIGS. 3-3A. In this way, the conductive member300 is attached to the insulative shell 230. In example embodiments, theopenings 238 are disposed in the floor 232 of the insulative shell 230,particularly, at the edge of the floor 232. The first tabs 330 may bedisposed at an edge of the conductive sheet 302 and bendable at an anglerelative to the conductive sheet 302.

In the embodiment illustrated in FIGS. 3 and 3A, the first tabs 330 arebent at an angle, such as about 90 degrees, relative to the conductivesheet 302. Each of the openings in the insulative shell 230 has a pairof opposed slots 2382. The first tabs 330 are inserted into the slots2382 of corresponding opening 238. This both holds the conductive member300 against the insulative shell 230 and sets the position of theconductive member 300 relative to the columns of contacts. In differentembodiments, the angle of slots 2382 relative to horizontal directionmay be different to accommodate first tabs 330 bent angle(s) other than90 degrees.

In other embodiments illustrated in FIGS. 5 and 5A-5B, the first tabs510 of the conductive member 500 are slidable in the openings 520 in theinsulative shell 500. The openings 520 may have a configuration that issimilar to or different from the opening 238 shown as FIGS. 3 and 3A. Inthe case that the opening 520 is similar to the opening 238, the firsttabs 510 may be bent at less than 90 degrees. The first tab 510 are notinserted into the slots of the openings 520, instead, the sides of thefirst tabs 510 press against walls of larger openings 520, as shown inFIG. 5A. In this way, the first tab 510 is slidable in the opening 520.A benefit of this slidable connection is that the conductive member 500is positioned relative to the columns of contacts based on the shape ofthe insulative shell 500 around the contacts. This avoids misalignmentof the conductive member 500 relative to the contacts. It is found thatmisalignment of the conductive member 500 and contacts resulted in theconductive member 500 scraping along the edges of the contacts duringassembly. This scraping caused metal to be scraped off the contact,which could interfere with operation of the connector.

In some embodiments, the conductive member 300 further includes a secondplurality of tabs 340, as shown in FIGS. 3 and 2A. Each of the secondtabs 340 is disposed in each of the second openings 320. Each of thesecond tabs 340 presses against a corresponding second contact 220. Thesecond contacts 220 may comprise first surfaces, facing a firstdirection, and opposing second surfaces 2202. In the embodimentillustrated, the second contacts 220 are shaped as blades with the firstand second surfaces forming broadsides of the blades and edges joiningthe surfaces.

The second tabs 340 press against the second contacts 220 at the secondsurfaces 2202. In some embodiments, the second tabs 340 are compliantbeams. The compliant beams exert a spring force against the secondsurfaces 2202, biasing the conductive member 300 in a second direction240 normal to the second surfaces 2202. The first surfaces of the secondcontacts 220 may include mating surfaces of the second contacts 220 andmay be selectively plated with a noble metal, such as gold. Whendaughter card connector 120 and backplane connector 150 mate, contactsin the backplane connector and conductive elements in the daughter cardconnector mate to complete electrically conductive paths at the firstsurfaces.

In some embodiments, the second tabs 340 may comprise tips, and the tipsof the second tabs 340 are rounded. There are dimples 2204 that areconcave in the second surfaces of the second contacts 220. The tips ofthe second tabs 340 can contact the second surfaces of the secondcontacts 220 at the dimples 2204. In this way, pressing the rounded tipof the second tab 340 into the dimple 2204 makes two or more points ofcontact between the second tab 340 and the second contact 220, such thatthe second tabs 340 can make good electrical contact with the secondcontacts 220. However, any suitable contacting mechanism may be usedinstead of or in addition to dimples 2204 and the rounded tip of thesecond tab 340. Thus, the above description is not a limitation.

As mentioned above, the second tabs 340 bias the conductive member 300in the second direction 240. In order to counter this biasing force, thefloor 232 of the insulative shell 230 comprises a plurality of surfaceportions 234 and a recessed portion 236, as shown in FIGS. 3-3A. Therecessed portion 236 is recessed relative to the surface portions 234.The surface portions 234 extend through the first openings 310, as shownin FIG. 4A, and the conductive member 300 is disposed within therecessed portion 236. Accordingly, edges of the openings of theconductive member 300 abut the surface portions 234 so as to counterspring forces biasing the conductive member 300 in the second direction240. In the embodiments in which the first contacts 210 are disposed inpairs, each pair of the first contacts 210 extends through a surfaceportion 234. The second contacts 220 extend through the recessed portion236.

The floor 232 comprises a first surface, from which the mating contactportions of the first and second contacts 210 and 220 extend, and anopposed second surface, from which the contact tails of the first andsecond contacts 210 and 220 extend. In the example illustrated in thefigures, the first surface corresponds to the upper surface of the floor232, and the second surface corresponds to the lower surface of thefloor 232. The recessed portion 236 comprises a recess in the firstsurface. In some embodiments, the conductive member 300 is recessedbelow the floor 232 of the shell. This positions the conductive member300 by counters the forces exerted by the second tabs 340 against thesecond contacts 220. All second tabs 340 press the same direction,because the second tabs 340 should press on backs (second surfaces) ofthe second contacts 220. Fronts (first surfaces) of the second contacts220 have the contact surface and are plated with gold. Gold would bescraped off if the second tabs 340 were to slide along the front as thesecond contacts 220 are inserted through the conductive member 300.

In some embodiments, each of the second contacts 600 comprises a matingcontact portion 610 and two contact tails 620, as shown in FIG. 6. Thedual beam contact tails are used to provide multiple points of contactbetween the second contacts and the backplane 160. Again, it should beappreciated that other numbers of contact tails and other types ofmating contact portion structures may also be suitable for the secondcontacts 600. The second contact 600 has a first (front) surface 601 andan opposed second (back) surface 602, as mentioned above. The firstsurface 601 has the contact surface and is plated with gold, and thesecond surface 602 has a dimple. A second tab of the conductive memberpresses against the dimple.

In some embodiments, the second contacts 600 comprise twisted regions630, which are connected between the mating contact portions 610 andcontact tails 620. Because of the twisted region 630, a line between thetwo contact tails 620 is transverse to the contact surface. In someembodiments, the line between the two contact tails is at an angle tothe contact surface between 35 and 55 degrees. This results in a viahole pattern in the backplane to which the connector is attached thatreduces crosstalk. It especially reduces crosstalk between two pairs ofvias carrying signals that are close to each other in a column.

In some embodiments, one of two adjacent second contacts is twisted in afirst direction relative to the contact surface, and the other of thetwo adjacent contacts is twisted in a second direction, opposite to thefirst direction, relative to the contact surface. As shown in FIG. 6,take two adjacent second contacts 610A and 610B for example, the contacttails of the second contact 610A are twisted in counterclockwisedirection relative to the contact surface, while the contact tails ofthe second contact 610B are twisted in clockwise direction relative tothe contact surface. Accordingly, it seems that the contact tails of thesecond contacts 610A and 610B face to each other. This feature isprovided to further reduce crosstalk between two pairs of signalconductors close to each other in a column.

Preferably, the connector comprises at least 16 second contacts, and theconductive member 300 electrically connects the at least 16 contacts asa common conductive member.

Any backplane connector mentioned above may be mounted to a printedcircuit board. The printed circuit board further comprises a pluralityof signal traces and a plurality of ground layers. The first contacts ofbackplane connector are connected to the signal traces, and the secondcontacts are connected to the ground layer.

The assembling of the electrical connector is described by reference tothe embodiment as shown in FIGS. 4-4A. Firstly, the conductive member300 is placed adjacent to the floor of the shell 230. The first tabs 350of the conductive member 300 extend into openings 238 in the shell suchthat the conductive member 300 is attached to the shell 230. Then, thefirst contacts 210 are inserted through the first openings in theconductive member 300 and the floor 232 of first contacts 210, and thesecond contacts 220 are inserted through the second openings in theconductive member 300 and the floor 232 of first contacts 210. In thismanner, the first and second contacts 210 and 220 are positioned incolumns on the floor.

In this embodiment, the first tabs are bent down to engage the slots ofshell. However, the manner by which the conductive member 300 isattached to the shell 230 is not limited to this. Alternatively oradditionally, the conductive member 300 may be attached to the shell byan interference fit, and/or smaller first tabs 510 and larger openings520 as shown in FIGS. 5-5A. The step of placing the conductive memberadjacent to the floor of the shell comprises receiving portions of theshell within the first openings. For instance, a plurality of projectingsurface portions 234 may extend into first openings 310, as shown inFIG. 3. The portions of the shell electrically insulate the firstcontacts from the conductive member. The second tabs may press againstthe second contacts such that the second contacts are electricallyconnected through the conductive member.

The step of inserting the second plurality of contacts comprises slidingeach of the second tabs over a second surface of the second plurality ofcontacts, to avoid the noble metal on the opposed first surface to bescraped off.

An example of a printed circuit board is described with reference toFIG. 7. A partial top view of backplane 160 showing a portion of aconnector footprint 700 for mating with the contact tails of backplaneconnector 150 is shown in FIG. 7. The backplane 160 may be implementedas a printed circuit board as described below. As shown, the connectorfootprint 700 includes a plurality of columns of repeating via patterns.FIG. 7 only schematically shows two via patterns 710 and 720, and theyare in different columns. In the illustrated embodiment, each viapattern includes two pairs of signal vias for forming two differentialpair of signal conductors, and two pairs of ground vias for formingassociated reference conductors. The via patterns 710 and 720 inadjacent columns may be offset by a distance D in a direction 730 of thecolumns such that Near End Crosstalk (NEXT) between adjacent pairs ofsignal vias, such as 712 and 722, in different columns can be reduced.

Take the via pattern 710 for example, it includes a first pair of signalvias 712 and a second pair of signal vias 714, as well as a first pairof ground vias 716 and a second pair of ground vias 718. Within eachcolumn, the pairs of ground vias are positioned between adjacent pairsof signal vias. The first pair of ground vias 716 is positioned betweenthe first pair of signal vias 712 and the second pair of signal vias714, and the second pair of ground vias 718 is positioned between thesecond pair of signal vias 714 and a first pair of signal vias inadjacent via pattern (not shown). Within each column, each pair ofsignal vias is positioned between a first pair of ground vias and asecond pair of ground vias. The first pair of signal vias 712 ispositioned between the first pair of ground vias 716 and a second pairof signal vias in adjacent via pattern (not shown), and the second pairof signal vias 714 is positioned between the second pair of ground vias718 and the first pair of ground vias 716.

In some embodiments, the centers of the signal vias 712 and 714 arealigned on a first line A-A in the column direction 730. For each pairof ground vias, the centers of the ground vias have different offsetsfrom the first line A-A in a direction perpendicular to the first lineA-A. For instance, for the pair of first and second ground vias 7162 and7164, the first and second ground vias 7162 and 7164 are offset from thefirst line in a direction perpendicular to the first line. Furthermore,the first and second ground vias 7162 and 7164 are offset from the firstline in opposite directions. The first ground via 7162 is offset fromthe first line A-A upwards, and the second ground vias 7164 is offsetfrom the first line A-A downwards, in FIG. 7.

The centers of the first pair of ground vias 716 are aligned on a secondline B-B, and the centers of the second pair of ground vias 718 arealigned on a second line C-C. In some embodiments, the second line B-Bmakes an angle a with the first line A-A, and the second line C-C makesan angle β with the first line A-A. In some embodiments, the angles aand I are in the opposite directions. The absolute values of angles αand β may be different or the same. These features are provided toreduce crosstalk between adjacent pairs of signal conductors in acolumn.

It will be understood that each of the via patterns 710 and 720 matchesa pattern of contact tails of backplane connector 150, as shown in FIG.1 and described above. In particular, each column of via patternscorresponds to one of the columns of contact tails of backplaneconnector 150. It will be understood that the parameters of theconnector footprint may vary, including the number and arrangement ofvia patterns and the configuration of each via pattern, provided thatthe connector footprint matches the pattern of contact tails inbackplane connector.

The disclosed technology is not limited in its application to thedetails of construction and the arrangement of components set forth inthe following description or illustrated in the drawings. The disclosedtechnology is capable of other embodiments and of being practiced or ofbeing carried out in various ways. Also, the phraseology and terminologyused herein is for the purpose of description and should not be regardedas limiting. The use of “including,” “comprising,” “having,”“containing,” or “involving,” and variations thereof herein, is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items.

Having thus described at least one illustrative embodiment of theinvention, various alterations, modifications and improvements willreadily occur to those skilled in the art.

For example, layers may be described as upper layers, or “above” or“below” other layers. It should be appreciated these terms are for easeof illustration and not a limitation on the orientation of layers. Inthe embodiment illustrated, “upper” refers to a surface of a printedcircuit board to which components are attached or a normal to such asurface. In some embodiments, components may be attached to two sides ofa printed circuit board, such that upper and lower may depend on whichvias are being considered. Such alterations, modifications, andimprovements are intended to be part of this disclosure, and areintended to be within the spirit and the scope of the present invention.

Further, it was described that each column of signal conductors within aconnector may comprise pairs of signal conductors with one or moreground conductors between each pair. In some embodiments, the signalconductors and ground conductors may be arranged such that two groundconductors are between each pair of signal conductors. Such connectorsmay have a footprint with pairs of signal vias 712, 714 with multipleground vias between each pair of signal vias, and, in some embodiments,with two pairs of ground vias 716, 718 between each pair of signal vias714.

Accordingly, the foregoing description is by way of example only and isnot intended to be limiting. The present invention is limited only asdefined in the following claims and the equivalents thereto.

1. An electrical connector comprising: an insulative shell having afloor; a first plurality of contacts extending through the floor,wherein the first plurality of contacts are disposed in a plurality ofcolumns; a second plurality of contacts extending through the floor,wherein the second plurality of contacts are interspersed with the firstplurality of contacts within the plurality of columns; and a conductivemember adjacent the floor, the conductive member comprising: a firstplurality of openings, wherein the first plurality of contacts extendthrough the openings of the first plurality of openings; a secondplurality of openings, wherein the second plurality of contacts extendthrough the openings of the second plurality of openings; and a firstplurality of tabs, extending into openings in the insulative shell. 2.The electrical connector of claim 1, wherein: the first plurality oftabs are slidable in the openings in the insulative shell relative tothe columns of contacts.
 3. The electrical connector of claim 1,wherein: each of the openings in the insulative shell has a pair ofopposed slots; and each of the first plurality of tabs is inserted intothe pair of opposed slots.
 4. (Current Amended) The electrical connectorof claim 1, wherein: the first plurality of contacts are disposed in aplurality of pairs; within each column of the plurality of columns, eachpair of the plurality of pairs is disposed between two adjacent contactsof the second plurality of contacts; and the conductive member reducesnear end crosstalk between a first pair and a second pair diagonallyadjacent to the first pair by at least 2 dB over the frequency rangefrom 5 to 28 GHz.
 5. (canceled)
 6. The electrical connector of claim 1,wherein: the first plurality of contacts are disposed in a plurality ofpairs; within each column of the plurality of columns, each pair of theplurality of pairs is disposed between two adjacent contacts of thesecond plurality of contacts; each of the second plurality of contactscomprises a mating contact portion and two contact tails, the matingcontact portion comprises a contact surface, and each of the secondplurality of contacts comprises a twisted region such that a linebetween the two contact tails is transverse to the contact surface. 7.The electrical connector of claim 6, wherein: the line between the twocontact tails is at an angle to the contact surface between 35 and 55degrees.
 8. The electrical connector of claim 6, wherein: a first of thetwo adjacent second contacts is twisted in a first direction relative tothe contact surface; and a second of the two adjacent second contacts istwisted in a second direction, opposite to the first direction, relativeto the contact surface.
 9. The electrical connector of claim 1, wherein:the floor comprises a plurality of surface portions and a recessedportion, recessed relative to the surface portions; the plurality ofsurface portions extend through the first plurality of openings; and theconductive member is disposed within the recessed portion. 10-13.(canceled)
 14. The electrical connector of claim 1, wherein: theconductive member also comprises a second plurality of tabs; the secondplurality of tabs press against the second plurality of contacts; thesecond plurality of contacts comprise first surfaces, facing a firstdirection, and opposing second surfaces; and the second plurality oftabs press against the second plurality of contacts at the secondsurfaces.
 15. The electrical connector of claim 14, wherein: the secondplurality of contacts comprise dimples that are concave in the secondsurfaces; the second plurality of tabs comprise tips; and the tips ofthe second plurality of tabs contact the second surfaces at the dimples.16. The electrical connector of claim 15, wherein: the tips of thesecond plurality of tabs are rounded such that the tips contact thedimples at at least two points.
 17. The electrical connector of claim14, wherein: the second plurality of tabs are compliant beams and exerta spring force against the second surfaces, biasing the conductivemember in a second direction normal to the second surfaces; the floorcomprises a plurality of surface portions and a recessed portion,recessed relative to the surface portions; the plurality of surfaceportions extend through the first plurality of openings such that edgesof the conductive member abut the surface portions so as to counterspring forces biasing the conductive member in the second direction. 18.The electrical connector of claim 14, wherein: the first surfaces of thesecond plurality of contacts comprise a selective plating of gold. 19.The electrical connector of claim 1, wherein: the second plurality ofcontacts comprises at least 16 contacts; and the conductive memberelectrically connects the at least 16 contacts; the first plurality ofcontacts comprise differential signal contacts; and the second pluralityof contacts comprise ground contacts. 20-22. (canceled)
 23. Theelectrical connector of claim 1, in combination with a printed circuitboard, the printed circuit board comprising: a plurality of signaltraces; a plurality of ground layers; and wherein the electricalconnector is mounted to the printed circuit board, wherein: the firstplurality of contacts are connected to the signal traces; and the secondplurality of contacts are connected to the ground layers. 24-33.(canceled)
 34. An electrical connector comprising: an insulativehousing; a first plurality of contacts held by the housing, wherein thefirst plurality of contacts are disposed in a plurality of pairs in aplurality of columns; and a second plurality of contacts held within thehousing, wherein within each column of the plurality of columns,adjacent pairs of the plurality of pairs are separated by at least onecontact of the second plurality of contacts; wherein: each of the firstplurality of contacts comprises a mating contact portion and a contacttail; each of the second plurality of contacts comprises a matingcontact portion and two contact tails, the mating contact portioncomprising a contact surface, and each of the second plurality ofcontacts comprises a twisted region such that a line between the twocontact tails is transverse to the contact surface.
 35. The electricalconnector of claim 34, wherein: the line between the two contact tailsis at an angle to the contact surface between 35 and 55 degrees.
 36. Theelectrical connector of claim 34, wherein: each pair of the plurality ofpairs is, within a respective column of the plurality of columns,between two adjacent contacts of the second plurality of contacts. 37.The electrical connector of claim 36, wherein: a first of the twoadjacent contacts is twisted in a first direction relative to thecontact surface; and a second of the two adjacent contacts is twisted ina second direction, opposite to the first direction, relative to thecontact surface.
 38. The electrical connector of claim 37, wherein: thecontact surface of each of the second plurality of contacts isselectively plated with a noble metal.
 39. The electrical connector ofclaim 38, wherein: the first plurality of contacts comprise differentialsignal contacts; and the second plurality of contacts comprise groundcontacts.
 40. A printed circuit board with a connector footprint, theconnector footprint comprising: a plurality of columns of vias, each ofthe plurality of columns comprising: a repeating pattern comprising apair of signal vias and a pair of ground vias, wherein: the centers ofthe signal vias are aligned on a first line in the column direction: andfor each pair of ground vias, the centers of the ground vias havedifferent offsets from the first line in a direction perpendicular tothe first line.
 41. The printed circuit board of claim 40, wherein: foreach pair of ground vias, a first ground via of the pair and a secondground via of the pair are offset from the first line in a directionperpendicular to the first line.
 42. The printed circuit board of claim41, wherein: the first ground via and the second ground via are offsetfrom the first line in opposite directions.
 43. The printed circuitboard of claim 42, wherein: within each column, the pairs of ground viasare positioned between adjacent pairs of signal vias.
 44. The printedcircuit board of claim 42, wherein: within each column, each pair ofsignal vias is positioned between a first pair of ground vias and asecond pair of ground vias.
 45. The printed circuit board of claim 44,wherein: for each pair of ground vias, a second line through the centersof the ground vias makes an angle with the first line; the angles of thesecond lines with respect to the first line are in the oppositedirections for the first pair of ground vias and the second pair ofground vias.
 46. The printed circuit board of claim 45, wherein: eachcolumn of the plurality of columns is offset in the column directionwith respect to adjacent columns.